1. Field of the Invention
The present invention relates to a cartridge detachably mountable to a main body of an electrophotographic image forming apparatus and an electrophotographic image forming apparatus to which the cartridge is detachably mountable.
2. Related Background Art
Conventionally, as an electrophotographic image forming apparatus that can form a color image, there is known an electrophotographic image forming apparatus in which developer images of respective colors are sequentially formed on one photosensitive drum using a plurality of developing devices for different colors. In addition, as disclosed in Japanese Patent Application Laid-Open No. 2002-244531, there is known an electrophotographic image forming apparatus in which a photosensitive drum and respective developing devices are adapted as cartridges detachably mountable to a main body of an image forming apparatus. In the following description, a cartridge having the electrophotographic photosensitive drum is referred to as a drum cartridge and a cartridge having the developing device is referred to as a developing cartridge.
In the electrophotographic image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-244531, a guide member is provided on an inner side of a right side plate and a left side plate of a main body frame of the apparatus main body. A mounting and detaching guide and a positioning portion for the cartridges are provided in the guide member. This allows the developing cartridge and the drum cartridge to be easily mounted and detached from the apparatus main body. Further, the cartridge can be accurately positioned with respect to the apparatus main body.
The main body frame and the guide member are required to accurately position the cartridges with respect to the apparatus main body and have rigidity for stably holding the cartridges.
In realizing a reduction in cost and a reduction in size of the apparatus main body, it is conceivable to reduce the thickness of the main body frame and the guide member provided on an inner side of the main body frame. However, in this case, the main body frame and the guide member tend to undergo a deflection. When the main body frame and the guide member undergo the deflection, it is likely that positioning accuracy deteriorates in positioning the cartridges with respect to the apparatus main body.